Differences in serum cytokine levels between influenza virus A and B infections in children

Objective: To investigate differences in cytokine production between influenza A and B. Materials and methods: thirty one patients with influenza A and 16 with influenza B were enrolled in this study. We measured soluble tumor necrosis factor receptor (sTNFR) 1, interleukin (IL)-6, interferon (IFN)-γ and IL-4 concentrations in serum obtained from all patients during the acute and convalescence phases of their illnesses. Results: the sTNFR1 and IL-6 serum concentrations of patients with influenza A and B were equivalently elevated in the acute phase of their illness. However, the acute phase concentrations of IFN-γ and IL-4 were significantly higher in patients with influenza A than in patients with influenza B. The concentration of all cytokines in influenza A and sTNFR1 in influenza B significantly decreased from the acute to convalescent phase. Plotted from the onset of symptoms it appeared that all of the cytokines peaked within 24 h after onset. Discussion: the production pattern of the inflammatory cytokines – TNF and IL-6 – were the same between influenza A and B. However, a Th2 predominant cytokine pattern was induced after natural influenza virus A infection, notably IL-4 that differed from that to influenza B.